cavity nest preferences and locations of woodpeckers in wild basin, rocky mountain national park...

Cavity Nest Preferences and Locations of Woodpeckers in Wild Basin, Rocky Mountain

National Park

Peter DolanWinter Ecology, Spring 2012

Mountain Research Station, University of Colorado at Boulder

Ecological Importance

• Cavities can aid birds in thermoregulation–Wind and Sun Exposure

(Rendell and Robertson 1994)

• Snags and primary cavity nesters are critical to the stability of forest ecosystems (Wiebe, 2001)

Research Site

Research Questions

• What are the determining factors for woodpeckers in choosing a tree to use as a potential nest at Wild Basin?

• Where on a tree do woodpeckers create cavity nests and why?

Woodpeckers

Hairy WoodpeckerDowny Woodpecker

Northern Flicker

Research Methods

• Early set backs (questioning my methods)

• Scouting for snags• Document variables of cavity

locations– Tree Species– Cavity Aspect– DBH (diameter at breast height)– Cavity Height

Field Results

0 1 2 3 4 5 6 7 8 90

10

20

30

40

50

60

70

80

DBH of Observed Cavity Trees

Observed Cavity Trees

DBH

(cm

)

Mean DBH observed: 47.2North

South East

West NE

NW SE SW

1

2

3

0

4

2 2

4

Cavity Aspect

Discussion

• Cavity Aspect Hypothesis• Cavities faced open areas rather than dense

forest• Why were there no cavities in subalpine fir

snags?

Results Compared to Prior Research

• Hairy Woodpeckers nest in what ever habitat is available (Ripper et al, 2007)

• Broken canopy is a key variable in determining a tree in which to nest (Ripper et al, 2007)

• Prefer to nest in older trees with large DBH, in relatively open forest areas (Ripper et al, 2007)

Conclusions

• Importance of primary cavity excavators in forest ecosystems

• Cavity aspect • Broken Canopy and a large DBH are key

variables in choosing a nesting tree

Works Cited

• Landscape Use by Hairy Woodpeckers in Managed Forests of Northwestern Washington. Dana Ripper, James C. Bednarz and Daniel E. Varland The Journal of Wildlife Management , Vol. 71, No. 8 (Nov., 2007), pp. 2612-2623.

• Cavity-Entrance Orientation and Nest-Site Use by Secondary Hole-Nesting Birds Wallace B. Rendell and Raleigh J. Robertson Journal of Field Ornithology , Vol. 65, No. 1 (Winter, 1994), pp. 27-35.

• Microclimate of Tree Cavity Nests: Is It Important for Reproductive Success in Northern Flickers? Karen L. Wiebe The Auk , Vol. 118, No. 2 (Apr., 2001), pp. 412-421.